Speed governor for electric motors



Dec. 5, 1939. w. A. ANDERSON SPEED GOVERNOR FOR ELECTRIC MOTORS FiledJune 29, 1938 A\ N IIIIIII INVENTOR WALTER A. ANDERSON 1? ATTORNEYPatented Dec. 5, 1939 UNITED STATES PATENT OFFICE SPEED GOVERNOR FORELECTRIC MOTORS Application June 29, 1938, Serial No. 216,464

1 Claim.

This invention relates to electric contact speed governors such as areused on accounting machines and the like, and more particularly to aspeed regulating adjustment therefor.

I Adjustment devices of this character generally employ a set screwthreaded in the flexible contact feather and arranged to be adjustedtoward and from the actuating arm of a centrifugal govern'or. Such adevice is disclosed in United States Patent No. 1,984,512, issuod toWalter A. Anderson on December 18, 1934. An unsatisfactory feature ofthis method of adjustment is that it is impractical to make theadjustment while the machine is running, necessitating therefore,several adjustments by trial and error method until a satisfactoryoperating speed is obtained. Another disadvantage of this type ofadjusting device is that the governor housing must be removed in orderto gain access to the set screw.

An object of the present invention, therefore, is to provide anadjusting means for an electric contact governor which is readilyaccessible and permits the desired speed regulation while the machine isrunning.

With this and incidental objects in view, the invention consists incertain novel features of construction and combinations of parts, theessential elements of which are set forth in the appended claim, and apreferred embodiment of which is hereinafter described with reference tothe drawing which accompanies and forms part of the specification.

In the drawing:

Figure 1 is a perspective view of an electric contact governor embodyingthe invention,

Figure 2 is a right side elevation of the governor with the housingshown in section, and

Figure 3 is a sectional view taken on the line 33 of Figure 2.

The armature shaft I (Figures 1 and 2) has secured on its end a bracket2 of rigid construction. A flexible actuating feather 3 is secured atone end to bracket 2 by screws 4 and carries a weight 5 at its otherend, the center of mass of the weight being normally to the left (Figure2) of the plane of rotation of the pivot point of feather 3, the pivotpoint being designated by the numeral 6. Feather 3 is of two-partconstruction, as shown, one of the parts having a go round boss Ilocated at the axis of rotation of the armature shaft and feather. Arigid contact support 8 fixed on two sleeves II (Figure 3) is supportedfor sliding movement on two studs I2, and is held out of electricalcontact with the studs by insulating material as shown. The support 8carries a bearing I3 (Figures 1 and 2) in which is slidably supported aplunger I4 of hard insulating material. A cross bar I5 is mounted ininsulated condition on studs I2 and is secured in spaced relation tosupport 8 for sliding move- 5 ment therewith by screws I6 passingthrough insulating bushings and collars I1 and threaded in the support.A contact feather I8 is fixed on bar I5 for sliding movement on studsI2,

and is likewise held out of electrical contact with 10 the studs byinsulating material as shown. A thumb screw 2| journaled in a stationarybar 22 spanning and insulated from the ends of studs I 2 is threaded incross bar I5 (Figures 1 and 3) to adjust support 8, plunger I4 andfeather I8 as 15 a unit, bodily toward or away from actuating feather 3.Nuts 23 threaded on the ends of studs I2 hold the parts in assembledposition as shown.

A knob 24, preferably of insulating material, is fixed on screw 2|, andextends through an aper- 20 ture in the governor housing (Figure 2) soas to be readily accessible. Feather I8 carries a set screw 25 in axialalignment with plunger I4, and carries a contact 21 to cooperate with asimilar oppositely disposed contact 26 secured in support 25 8. Wires2'8 and 29 carry current through support 8, contacts 26 and 21, andfeather I8, and from there to the electric motor (not shown) so that themotor is supplied with current only while contacts 26 and 21 are closed.When current is 30 started through wires 28 and 29 and through themotor, armature shaft I starts rotating, whereupon weight 5 moves to theright about pivot 6 (Figure 2). Its amount of movement to the rightincreases with the speed of rotation of 35 armature shaft I. As weight 5and feather 3 move to the right, boss 1 slides plunger I4 to the right,contacting the left end of set screw 25. Further acceleration ofarmature shaft I results in additional movement of the plunger I4 to the40 right, causing feather I8 and contact 21 to be moved to the rightaway from contact 26. This breaks the circuit to the motor, causing itto decelerate until Weight 5 and the associated parts return a shortdistance to the left, at which 45 time contact 21 again touches contact26, re-establishing the circuit. When these parts find theirequilibrium, contacts 26 and 21 are made and broken in such rapidsuccession that the motor runs at a speed that is sufiiciently constantfor practical purposes.

When it is desired to increase or decrease the speed of the machine, itis merely necessary to turn knob 24 clockwise or counter-clockwiserespectively (Figure 1) to bring the contact unit 2t2l and plunger 06farther from or nearer to the actuating feather 8. Adjustment of thespeed in this manner can he made while the machine is g because the oithumb screw 28 has no uence on the tension of one contact against theother. Rotation of knob 26 clockwise causes screw it to increase thedistance between feather 3 and plunger l l causing contacts 26-21? tobreak later and thereby increase fine speed of the machine. Conversely,rotation of lsnnob 2t counter-clockwise decreases the distance betweenfeather 3 and plunger it, causing contacts 2t-tl to break sooner andthereby reduce the speed of the machine. The thread of screw 20 is muchfiner than thatshown in the illustration in Egure 3, this thread beingenlarged in the showing for clearness of illustration, making possible avery fine adjustment of the speed.

While the form of mechanism herein shown and described is admirablyadapted to i the objects primarily stated, it is to be understood thatit is not intended to confine the invention to the one form ofembodiment herein disclosed, for it is susceptible of embodiment invarious aisaiii forms all coming within the scope of the claim whichfollows.

. What is claimed is:

In a speed governor for an electric motor, a rotatable shaft, a bracketsecured to one end thereof, an actuating feather having one end securedto the bracket and the opposite end provided with a weight and beingfree to move in a direction substantially parallel with the axis ofthe'shaft in response to changes in the speed of rotation of the shaft,a. stationary support, a rigid contact leather and a flexible contactfeather, a carriage slidable on the stationary support and havingsecured thereto one end of each of the contact feathers, a. plungerslidably supported in the rigid contact feather at the axis of rotationof the shaft, one end of the plunger lying adjacent a portion of theflexible contact feather and another portion of the plunger lyingadjacent a portion of the actuating feather, and a micrometer adjustingmeans for moving the contact feathers and plunger bodily toward or awayfrom the actuating feather.

WALTER A. ANDERSON.

